Update git submodules

* Update docs/submodules/dmaap/datarouter.git from branch 'master'
  to 51f0b1c075a7503335af71358ffaf62f7ffe9471
  - add additional unit tests for feed
    
    Change-Id: Ic9346b1af0ad0ad845e5d001bc3ee23e128417dc
    Issue-ID: DMAAP-1119
    Signed-off-by: EmmettCox <emmett.cox@est.tech>
    
1 file changed